Or NEVER release an address (except to trusted friends) that isn't a disposable alias - eg.
http://www.spamgourmet.com
http://www.spammotel.com
The Mailinator service is not much help if you need to send - but is great if you want a zero-commitment address to receive a one-time signup email - and remember the short retention - if you expect an email on Mailinator, you need to be checking every few hours, so it's no use for anything where they may legitimately want to contact you.
Spammotel lets you "lock out" an address if it's abused.
Spamgourmet lets you "charge" an address with a certain number of receives, recharge it, terminate it, or create/terminate an unlimited alias - Giving 3 messages allowed is probably enough to handle most single "transactions", without much leeway for abuse.